Tech Topics By Joe Muscolino, Sturtevant, Inc. Air Classification for Low-ash Meal Processing Of all the rendered poultry products produced annually, an estimated 25 percent is currently being processed into the key protein ingredient used in dry pet foods. Poultry protein meal, which can be up to 40 percent of the typical pet food formula, accounts for more than 85 percent of dietary protein and 30 percent of dietary fat in pet food nutrition. Necessary for proper digestion, the pet food-grade product must meet low ash/high protein parameters. In doing so, its value is approximately twice that of a regular ash/protein poultry meal material. As such, renderers continually seek the most effective processing solutions to increase the yield of a premium pet food-grade product. In large part, it all comes down to the basics – employing the most cost-efficient methods of separating out the coarse material common to poultry meal and capturing the fine material for the premium product. As an alternative to conventional vibrating or high-frequency screens, which are often susceptible to binding, renderers are finding that air classification technology is ideally suited for this challenging application. Sanimax Pursues New Pet Food-grade Market Recently, Sanimax expanded into the pet food-grade meal market when it incorporated air classification technology into the heart of a series of plant upgrades in its Montreal, Canada, location. The company operates 15 facilities throughout Canada, the United States, and Mexico offering a range of by-product collection services and has long been a leading supplier of feed ingredients for agriculture and animal nutrition. “Prior to acquiring the air classifier, we were producing poultry meal alone,” noted Sanimax process specialist Jean- Luc Champoux. “However, our Canadian customers started asking for a high-quality pet food-grade product as well, so we decided to retool and expand to meet their needs.” As Sanimax researched its expansion approach, it was led early on to the concept of air classification. Ultimately, it found the technology would essentially allow the renderer to double its returns by making one product into two. By separating out the fines, the poultry meal could be converted into a high-value pet food grade. At the same time, the coarse fraction still contains enough protein that it can be processed as regular poultry grade feed. Specifying the Right Classifier Sanimax consulted with Sturtevant, Inc., a Hanover, MA-based company with more than 80 years of classifying experience in countless applications, among them a growing number of global installations within large poultry and protein meal production operations. “We chose them due to their experience, engineering, and communications skills,” said Champoux. “They also offer the ability to test our product specifications in their lab and to work with us onsite to ensure that the equipment is meeting our requirements.” The test phase began with the shipment of 2,000 pounds of material to the Sturtevant labs, where Champoux and his quality control manager joined the Sturtevant research team to observe the process and examine the results. First, the team wanted to determine which classifier model would be suitable for the application. Tests were conducted on both internal and external fan models. “We needed a unit that would perform under abrasive conditions, with minimal clogging, and deliver the desired product yield,” Champoux stated. Tests determined that processing parameters and end product requirements were met and even exceeded by the specification of a 4½-foot Whirlwind Classifier, a unit that does not require auxiliary equipment (baghouses, cyclones, or ductwork) to capture the lower ash and higher protein fine product. Since the model features an internal fan and air recycle design, the fluidized meal is resistant to clogging and there are minimal dead zones where high fat and sticky material can settle. Testing Product and Processing Quality A second round of testing generated specific data on ash reduction and protein increase in the production of pet food-grade meal as well as ascertain how product yields would correlate with overall product quality. The classifier was adjusted during the test process to target and refine desired specifications. To confirm and measure the levels of ash, protein, moisture, and fat, samples were shipped to Sanimax for analysis. This allowed the renderer to verify all the parameters in its own lab for assurance of the end result. “We established a close working relationship during the testing process,” explained Champoux. “Plus, being onsite for the research work allowed us to be trained on how to properly operate, adjust, and maintain the air classifier.” The third and final segment of testing involved placing a trial machine in the Sanimax facility along with a Sturtevant service technician to aid in proper setup and ongoing machine adjustments. As lab testing could only be conducted in ambient (70 degrees Fahrenheit, 21 degrees Celsius) temperatures, there was the concern that actual processing temperatures (up to 160 degrees Fahrenheit, 71 degrees Celsius) would cause the heated fat content in the meal to affect machine performance or cause clogging. Importantly, Sanimax wanted to determine whether the meal would become stickier, resulting in lower efficiency in the classifier’s ability to separate the lower ash and higher protein fine fraction from the coarse fraction. “We wanted to make sure that any machinery we bought would not clog, especially during the first week of operation, as we did expect the application to be somewhat sticky,” said Champoux. “The test revealed only a slight accumulation of material and no problems in the separation of the product.” 30 December 2013 Render www.rendermagazine.com
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